JPH11504447A - Spatial magnetic inquiry - Google Patents

Abstract

(57) SUMMARY A magnetic tag or marker and various techniques by which such tags can be queried are disclosed. In one aspect, a magnetic marker or tag is characterized by retaining a plurality of discrete magnetically active regions in a linear array. In another aspect, the invention provides a method for querying a magnetic tag or marker in a predetermined inquiry zone, wherein the tag comprises a highly permeable magnetic material, wherein the highly permeable magnetic material comprises, for example, Reading the data stored magnetically on the tag or using the response of the tag to detect its presence and / or to determine its position within the inquiry zone, the invention relates to an inquiry process. Includes sequentially exposing the tag to (1) a magnetic field having sufficient strength to saturate the highly permeable magnetic material, and (2) a magnetic field null as defined herein. Examples of the application of such techniques include (a) identification of attached tags, (b) high-precision positioning, such as at the location of a surgical probe, and (c) the quality and cost of each item. Described in connection with the calculation of totals for purchases, holding tags coded by the data they represent.

Description

DETAILED DESCRIPTION OF THE INVENTION                               Spatial magnetic inquiry   The present invention relates to the implementation of magnetic properties within the scope of practical technology, Or use a new technology of spatial magnetic interrogation in connection with identification tags You. More specifically, but not exclusively, the present invention relates to a magnetic marker in an inquiry zone. A method for determining the presence and / or location of a car or tag; Methods to distinguish (eg, a given tag to distinguish it from others) ), A system for implementing these methods, such a method Tags for use in systems and systems, as well as recording data on such tags. And remotely searching for data from such tags later.   The terms "tag" and "marker" used here are interchangeable Which can be used in many different applications, and (A) The presence of a tag (and the presence of an object with that tag), depending on the mood quality Or (b) indicating the identity of the tag (and the identity of the object on which it is attached); Specifies the exact location of the tag (and the one with it) for a given coordinate Or (for example, to enter a protected area or, for example, a public transport network To give an access code, or generally something for ticketing purposes at Or it is used to distinguish one set of things from another.   Further, the terms “ac field” and “DC field” used herein are used. Words have properties associated with electrical conductors that carry alternating current (ac) or direct current (DC) Means magnetic field.   The tags, methods and systems of the present invention have a variety of applications as indicated above. You. These include inventory management, ticketing, automated purchasing systems, work progress monitoring, Security tagging, access control, anti-counterfeiting, and object location ( In particular, [e.g. the exact positioning of the tool]. However, it is not limited to these.)Prior art   Several passive data tag systems are currently available. Most widely used What is known as a bar code is a print pattern of optically readable lines. Turn based. The tag element of such a system is typically Because it is ink and paper, the cost is very low. The reader is also relatively costly Low, typically using laser beam scanning. In many applications, Barco The real drawback of the card is that it requires a line of sight between the reader and the tag.   In applications where line-of-sight is not possible, systems without optical transmission have been developed. Have been. The most popular is between tags and introgator electronics Use magnetic induction for coupling. These are typically 50 kHz to 1 MHz Operates in an alternating magnetic field in the frequency range and generally handles receive and transmit functions Integrated electronic circuits ("chips") to provide additional data storage and manipulation ) Is used. To avoid needing a battery, the power for the chip is Obtained by rectification of the interrogation signal received by the antenna coil. Tell To increase power and to distinguish against unwanted signals and interference First, the coil is resonated with a capacitor at the frequency of the interrogation signal carrier frequency. This A typical product of the type is a TI manufactured by Texas Instruments. RIS system.   Other multi-bit data tag systems use traditional high-frequency wireless technology, or surface A technology based on acoustic waves or magnetostriction is used.The present invention   The invention particularly relates to the use of a new kind of passive data tag system, Use a small amount of magnetic material with very high permeability, and use a scanned magnetic field for inquiry. Used. Since magnetic materials can take the form of thin foils, wires or films, On a substrate, for example on paper or plastic material, to form a self-supporting tag, Can be combined directly.   Alternatively, the magnetic material can be incorporated into the structure of the object to be tagged. Therefore, the tag attaches magnetic material to the surface of the object or places the magnetic material inside the body of the object. By embedding in the object, it can be formed in the original place of the object in question.   The present invention utilizes a magnetic field that includes "magnetic nulls," and the term "magnetic nulls" Means a point, line, surface or volume of space whose components are zero in a given line direction Used as a thing. The space volume that can satisfy this condition is very small May result in a particular embodiment of the present invention where the exact positioning is determined. Typical Typically, magnetic nulls exist in a relatively small linear range. Where there is a magnetic null , The component of the magnetic field in a direction orthogonal to a given linear direction can be substantial It is understood that this is the case more often. Some embodiments of the present invention Thus, such substantially orthogonal fields are desirable.   One way to create magnetic nulls is to use an opposite magnetic field source. They are A coil of wire carrying current, or a permanent magnet (suitable for small systems), or Or a combination of a coil and a permanent magnet. One coil or permanent magnet When used, it is also possible to implement magnetic nulls that exist in a particular direction.   For large scale applications, the magnetic field source is preferably a coil carrying a direct current.   The present invention uses a magnetic marker to mark the passage of the marker to the magnetic null. The relative movement between the applied magnetic field is used. This is a measure for the applied magnetic field. A magnetic field is generated by moving the car or while holding the marker in a fixed position. This is achieved by scanning on it. In general, the invention relates to (i) (magnetic At zero magnetic field (at null) and (ii) at a high, generally saturated magnetic field. The difference in the magnetic aspect of the car is used.Tags of the present invention   According to one aspect of the invention, a plurality of separate magnetically active elements in a linear array are provided. Provided are magnetic markers or tags characterized by having a sexual region. Another The magnetically active area is supported on a substrate such as paper or plastic material, for example. Or be supported by yourself. Alternatively, the magnetic element is manufactured in the article itself Can be incorporated into or on the article. This is, for example, Is a product, for example a retail item with a tag for inventory purposes, or Suitable if the is a ticket or security pass.   The above tags can be formed in a continuous strip with high magnetic permeability, The magnetic properties of the individual regions are changed permanently or temporarily. like this The process can begin at a selected region of the band having a high magnetic permeability, generally Processed to alter its magnetic properties by removing or reducing magnetic permeability Or positioned very close to high permeability magnetic material, e.g. High magnetic permeability with a magnetizable strip positioned above or adjacent to Strip of conductive material with selected areas magnetized. Relatively simple fruit In embodiments, each magnetically active region has the same magnetic properties, but in more complex embodiments, Each magnetically active region can have different magnetic properties, thereby making each one unique With unique magnetic identification and signature (appropriate reader Thus, a large number of tags having the same (if processed) can be assembled.   Since the present invention uses relative movement between the tag and the applied magnetic field, the tag reader The time domain of the output signal from the device and the gap between the magnetically active area of the tag and the magnetically active area It will be appreciated that there is a correspondence between the size in terms of the length between caps. This meaning , The active region and the gap between them are separated by the elements of the optical barcode ( Black bars or white gaps between adjacent bars). This The variability of the magnetic properties of the active region is used to create part of the tag's “identification”. Also use a linear space between adjacent magnetically active regions so that Can be. A vast number of tags, each with a unique identification, can be created in accordance with the present invention. It will be understood that   Although the tag is described as having a linear array of magnetically active regions, May actually have more than one such linear array. These are parallel to each other Or orthogonal to each other or in a desired geometric arrangement. like this Parallel and / or orthogonal arrays are preferred to simplify tag reading .   A suitable technique for manufacturing the tags of the present invention is to use conventional labels (ie, magnetic markers). Well known in manufacturing. Suitable magnetic materials are also well known and widely available Yes, preferably at least 10^ThreeHighly permeable material with extrinsic relative permeability It is. The coercivity of the magnetic material depends on the intended use of the tag. Magnetic materials preferred Or in the form of long, thin strips or thin films, Avoid the effects. Suitable strip materials are, for example, Vacuum Schmelze (Va cuumschmeltze) (Germany), Allied Signal Corporation (Allied Sig) nal Corp. ) (USA), and easy from commercial suppliers like Unitika (Japan) Can be obtained. For retail security tag applications, IST ( (Belgium) is also suitable for use in the present invention in thin film materials manufactured in large quantities. .Detection / identification method   In addition to the tags defined above, the present invention detects the presence of a magnetic marker and And / or provide a variety of useful methods for identifying such markers. In many cases, these methods are intended to be used in connection with the tags of the present invention. However, this is not a prerequisite for the method of the present invention.   According to a second aspect of the present invention, a magnetic tag or marker in a predetermined interrogation zone Is provided, and the tag is, for example, data stored magnetically on the tag. To read the tag or to use the response of the tag to detect its presence, And / or has high magnetic permeability to determine its position within the inquiry zone Inquiry method includes sequentially exposing the tag to a magnetic field having a sufficient magnetic force. Saturates magnetic materials having high magnetic permeability, and (2) the magnetic properties defined herein Exposing to null.   Preferably, the magnetic null sweeps back and forth a predetermined area within the interrogation zone. The scanning frequency (ie, the sweep frequency of the magnetic null) is preferably relatively low, For example, it is 1-500 Hz. For convenience, the field pattern is (a) the magnetic null Exists in the plane, and (b) the saturation field occurs adjacent to said plane. Placed in   According to a third aspect of the present invention, the magnetic element within a predetermined interrogation zone A method is provided for determining the presence and / or position, wherein the magnetic element The method comprises the steps of: (1) providing a magnetic element in the inquiry zone; Magnetic field is sufficient to saturate all or part of the Magnetic field including a relatively small area of zero magnetic field (magnetic null) adjacent to an area Establishing a pattern, said relatively small area being passed by a magnetic element, or Or the area that can or should pass, and (2) the magnetic field Causing relative motion between the magnetic elements and the magnetic null Crossing at least a portion of the magnetic element in the manner of (3), Characterized by detecting the magnetic response provided by the magnetic element during movement Attached.   According to a fourth aspect of the present invention, identifying a magnetic element having predetermined magnetic properties A method of (1) locating at least a portion of a magnetic element Exposing the magnetic element to a first magnetic field sufficient to cause magnetic saturation ) Next, the magnetic element is exposed to zero magnetic field (ie, magnetic null) conditions, Occupies a relatively small volume and is adjacent to the first magnetic field; A relative movement between the magnetic element and the magnetic element causes the magnetic null to be in a predetermined state. (4) the relative movement of at least a portion of the magnetic element Characterized by the step of detecting the magnetic response caused by the magnetic element during Can be   In the identification method specified above, the magnetic element generates the necessary magnetic conditions. It advantageously traverses within the query zone that is created.   According to a fifth aspect of the present invention, there is provided a magnetic element having predetermined magnetic characteristics. Provide a way to identify The method is characterized by the following steps Things. (1) Put the magnetic element into the inquiry zone. In the inquiry zone In areas where there is sufficient magnetic field to saturate the magnetic element or a part thereof ( A magnetic field pattern including a relatively small area of zero magnetic field (magnetic null) adjacent to a saturation magnetic field) Has been established. (2) Moving the magnetic element through the saturation magnetic field Try to reach the null. (3) The magnetic null is a magnetic energy in a predetermined manner. Between the magnetic field and the magnetic element so as to cross at least a part of the element. Causes relative motion. (4) The resulting magnetic element during said relative movement The magnetic response of the robot.   The relative movement between the magnetic element and the magnetic field is advantageously marked above the magnetic element. It can be generated by sweeping an applied magnetic field. Instead, this relative Motion is created by applying an alternating magnetic field to a generally static magnetic field pattern. Can be   In carrying out the above method, a preferred embodiment of the magnetic element is an elongated one. Wherein the magnetic null is arranged to extend along a main axis of the magnetic element Or in the form of a thin film, where the magnetic nulls Either one that is arranged to extend in alignment with the axis of the degree is good.   The magnetic field or magnetic field pattern used in the method defined above is of opposite polarity. It can be established by two pairs of magnetic fields. This is one that carries DC Using more than one coil or using more than one permanent magnet Or by combining coils and magnets Become.   When using coils, arrange them so that they carry a substantially constant current. The magnetic null may be maintained at a fixed point. Instead, 1 One or more coils carry a current of varying magnitude at a predetermined period. And the position of the magnetic null vibrates in a predetermined manner. In this specification Describes this as a "flying null". One or more coils and permanent magnets A similar arrangement may be used to obtain flying nulls when No.   According to a further aspect of the present invention, a magnetic device characterized by the following steps: A method is provided for determining the presence and / or location of an element. (1) Magnetic field Is applied where the magnetic element is or is expected to be. This Magnetic field contains two opposing magnetic field components produced by a magnetic field source, which results in Intermediate position of the magnetic field source (this position is known or can be calculated ) To generate a null magnetic field (magnetic null). (2) The magnetic field and the magnetic energy A relative movement is generated with the element. (3) the resulting relative luck The magnetic response of a moving magnetic element is detected.   The relative motion between the magnetic field and the magnetic element is determined by the ratio superimposed on the DC field. This may be possible by applying an alternating magnetic field of relatively small amplitude. Generally, this Such an alternating magnetic field having a small amplitude is 10 Hz to 100 kHz, preferably 50 Hz. Has a frequency in the range of from 50 kHz to 50 kHz, most advantageously from 500 Hz to 5 kHz .   In some embodiments, the coil carries a substantially constant current and maintains a magnetic null at a fixed point. You. In another embodiment, the coil carries a current that varies in amplitude at a predetermined period. Therefore, the position of the magnetic null oscillates in a predetermined manner.   In the method according to the invention, the detection of the magnetic response of the magnetic element is performed by applying an applied AC Includes observations of field harmonics, which cause the magnetic element to The passing state causes a change in the magnetization state, which is generated.   As described above, this system has zero or very low frequency scan fields, And HF (high frequency) in the range of 50 Hz to 50 kHz. This is Consideration is given to the good penetration of many materials, including thin metal foils. You. In addition, international regulations recognize that high magnetic fields are transmitted at these low frequencies. Have been.   The preferred embodiment of the present invention utilizes low frequency inductive magnetic interrogation and is complex and expensive. Provide a multi-bit data tag system that does not require a tag.   According to another aspect of the present invention, the properties of the object, such as the price of the object and / or the The data indicating the properties of the composing products makes it possible to A method is provided for coding and / or labeling an object. Of this method The features are: A predetermined, specific to the thing and other things that share the nature of the goods that make up To provide a magnetic tag or marker having a magnetic zone in an arranged arrangement. this Magnetic tags or markers are susceptible to referrals by the applied magnetic field, and Indicates the magnetic properties of the marker, i.e. the properties of the object with the magnetic tag or marker Generates a response indicatingBasis of invention   Before describing further embodiments, a relatively simple embodiment will be described where appropriate. It will be helpful to quote and describe some basic aspects of the invention .   An important aspect of the present invention is that the The type of magnetic field that is generated. This magnetic field interrogates a very small spatial area. Can be The means for generating this magnetic field is hereinafter referred to as "into Logger ”. This introgator, in one simple form, is Consisting of pairs of identical coils closely spaced. This coil is The directions are opposite and they are connected so that the DC current passes. This allows the coil shaft , An opposite magnetic field is generated. Occurs in the middle of the coil along the axis. The level of current in the coil is two coils A large sample of highly permeable magnetic material located in the center of either It's like saturating. Very small amplitude AC currents are also Flow in the opposite direction through the The sum occurs in the middle between the coils. This involves a return to ground and the two coils This is easily possible by connecting a suitable current source to the junction. This AC current Is generally about 2 kHz, but this value is not The numbers are widespread. This AC current interacts with the magnetic tag and is detectable Result in a query field that yields a good response. Another effect of this AC current is that The position of the magnetic field, i.e., the magnetic null, is only slightly around the middle position along the coil axis. (This is better than some very large excursions) Wobble or oscillation).   In addition, additional low frequency AC current is applied to the coil to provide a low frequency scan field. (Which may be 0). The frequency of this scan field is Many periods of the relatively high frequency query field (when present) Must be low enough to occur when the airspace passes over the tag. No. In general, the frequency (ω_a) Scan field frequency (ω_b ) Is on the order of 100: 1, but has a detrimental effect on the operation of the invention. Can be varied over a fairly wide range without giving You will understand.   Place a tag containing one highly permeable magnetic material in a location where oscillation of the magnetic zero plane occurs. When passed along the coil axis through the area below the Will be completely saturated by the world. Next, when passing through the zero magnetic field area, It will be driven temporarily above the BH loop. Finally saturated again Will be. The area above where the magnetic material is "active" is the magnetic The area that is undergoing change is physically small, with the amplitude of the DC field, And the characteristics of the magnetic material. This area is easily large Can be less than 1 mm. The level of the alternating magnetic field is Harmonics of the AC signal, well below what is needed to saturate the Indicates that the tag enters the zero field region of the introgator field and changes Will occur when responding to the password. Tags span a narrow zero field Driven by the linear part of the BH loop, diverging only the fundamental query frequency Will interact. Therefore, the tag moves away from the zero magnetic field region Occasionally, it will again emit harmonic interrogation field frequencies. 0 field It is arranged to be more sensitive to the generated magnetic field, but Receiver coils that do not couple directly to the receiver will only receive such signals. The change over time of this signal as the tag passes along the coil axis causes a zero field The passage of both ends of the magnetic material through the area is clearly shown.   Because the interrogation zone can be very narrow, individual magnetic materials It can be distinguished from its neighbors that are separated by a distance. Naturally, this magnetic material , The tags are selected to suit the particular application for which they are intended. Suitable magnetic materials are Less than It is commercially available as described below.   Tags with multiple zones or multiple magnetic materials along the axis of the label If considered, as each zone or each magnetic material passes through the zero field region, It will be appreciated that its presence and location at both ends can be detected. that way, Use specific lengths and spacings of individual zones or individual magnetic materials to Representing a sequence becomes easy. Many different coding methods Possible and one efficient arrangement is that the data is Coding method used for optical barcodes, represented by width and width Is to use the same one.   The above system is used for uniaxial tags (eg, for anisotropic materials having a magnetic axis along their length). Wire or thin strip) physically moves through the coil assembly Scanning the single-axis tag at the time is considered. Between tags and query fields Relative movement of the tag can be performed by resting the field and moving the tag, or vice versa. Noh. If necessary, make this method self-scanning, for example with two DC drive currents. By modulating the introgator coil of the It is possible to query stationary tags by scanning an appropriate part. The magnitude of this oscillation Must be at least equal to the maximum dimension of the tag, preferably The need for accurate tag positioning in the query zone by increasing the size Must be avoided.   By using additional coils placed on two axes orthogonal to the original Tag with random orientation can be read by sequential field scan . This involves a great deal of complexity in the correlation of signals from three planes, but is available Due to the very high spatial resolution, many tags that exist simultaneously in a common query volume Can be read. This is useful for applications such as tagging everyday retail goods Very useful for examples, eg automatic price of shopping bags at the point of sale (POS) It will allow for a sum calculation. As such, the present invention provides a And calculate sales (with or without inventory-related data processing) Applicable to point-of-sale (POS) systems.   The size of a simple linear tag depends on the length of the individual elements, their spacing, and the required It depends on the number of required data bits. Vacuum Schmelze (Germany) and Arai "Rotating molten" alloy foil, available from suppliers such as DoSignal (US) The use of commercially available strips of highly permeable material allows The minimum length of each element is probably on the order of a few millimeters. That The reason is that the very high intrinsic magnetic permeability (generally 10^Five) Rather than shape factors, It is superior to intrinsic magnetic permeability, and is not permeable for satisfactory operation when the length is short. That's enough.   For this reason, it is attractive to use very thin films of highly permeable magnetic material It is a target. If very thin (ideally less than 1 μm), high permeability is maintained So that the area is only 20mm^TwoThe following small two-dimensional pieces (square, Can be cut into discs. By doing so, the available high Elements shorter than those possible for elements made from permeable foil Tags are possible. Suitable thin film materials are commercially available from IST (Belgium) .   This type of programming can be expanded to include retail security systems. Can also be used to prevent compound tags from triggering alarms (such alarms It is a false indication of theft and bothers retailers and buyers. is there). If different areas of the tag are biased at different static field levels Generate signals at different times as they pass through retail security systems Will be. This complicates the label signature in such systems. Will prevent the occurrence of alarms. In the present invention, such a reading system is used. It is possible to handle a time-shifted signal caused by a strong magnetic bias.   For tag coding above, physically separate magnetic elements It has been described as a basis. However, physically separating the elements is important Programming data into tags is not This is possible by breaking the high permeability of the subsequent magnetic element. This is for example By heating locally above the recrystallization temperature of the amorphous alloy, or It is possible by punching or working materials. More importantly, intermediate and Is the magnetic field stored in the adjacent bias element made of high coercivity magnetic material. Magnetically isolates regions of continuous elements of highly permeable material Noh Power. Such a composite tag can be biased using a suitable magnetic recording head. You can easily code by writing a magnetic pattern on the element. Necessary If the tag is erased (by degaussing in the AC field), Can be reprogrammed.   The above method also works on tags that store data in two dimensions Can be extended. This allows for more compact tags. Because very good As in a convenient format, tags consisting of an N x N array of thin film fragments have the same number of tags. The coding potential is much higher than a linear array of pieces. This The reason is that more unique fragment correlations that can be set in a given area are Because there is.Further examples   Using spatial magnetic scanning for position sensing   In addition to the query space for reading the data tags, the plane of the zero magnetic field is moved into space. This new technology (or moving an object through a surface) uses a small material with high magnetic permeability. Can be used to provide accurate location information about items.   Thus, according to another aspect, the present invention provides a method for determining the exact location of an object. (A) fixing a small piece of magnetic material having high magnetic permeability to an object; (B) a magnetic field source generated by a magnetic field source in an area where the object is located; A magnetic field containing two opposite magnetic field components that produces a null magnetic field at the middle position between (C) applying a low-amplitude and high-frequency query field to said region (D) moving the position of the null magnetic field back and forth in a predetermined moving range. (E) applying the magnetic field and the magnetic material as described above; Observing the magnetic interaction between the particles of the sample and (f) the magnetic interaction described above. And related to the applied magnetic field and small pieces of magnetic material described above. Calculating the position of the object from the magnetic parameters of the object. Provide a way to Conveniently, small pieces of highly permeable magnetic material In the form of a wire, wire or thin film.   This aspect of the invention relates to a method wherein the object whose position is to be measured is a surgical instrument, Of particular interest, for example, when it is a surgical probe or needle. This invention For example, the position of the surgical probe during the operation is accurately determined.   This technique allows accurate positioning of very small markers within a relatively limited volume. Ideally, this allows multiple markers to be resolved separately. This is also outpatient Low sensitivity to metallic objects.   Magnetic tags or markers are typically similar to those used in EAS tags 1 cm (more if desired) amorphous wire (non-corrosive, 90 mm long) (Less than cron)) or, with proper process development, Short length (eg, 1 cm) needle sputter coated with a thin layer of magnetic material Can be   0.1 mm resolution at the described marker when used around the patient's head Can be achieved. Some calibration measures were taken and other magnetic materials were used. Accuracy may approach this value, but for optimal performance, A close, hard but open structure is desirable. The magnetic field levels used are the Lower than would be caused by a kitchen door clamp, for example).   This technique requires, in particular, three-dimensional and high-accuracy probe positioning. It is applied to brain surgery which is essential. Therefore, a small magnetic marker according to the invention Can be used on such probes or needles. In this case, the primary The only advantage is that the signal from the marker only needs to be detected and resolved when appropriate. The resolution is determined by the position of the zero magnetic field plane, and the detected marker signal It is not determined by the signal-to-noise ratio of the signal. For this reason, the The number of workers is very low.   A single axis position sensor with a set of coils similar to the tag reading system described above Is achieved. This is a set of opposites that carry DC current to create a DC magnetic field gradient. Marker in a small area where the DC magnetic field is close to 0 Means for applying a relatively uniform low-level AC magnetic field to introduce Variable intensity and polarity to move the position of the surface around the volume to be queried Means for applying a relatively uniform DC magnetic field.   Anisotropic markers, i.e. those with a preferential magnetic axis, move the magnetic field along its length Decompose. Such markers are, for example, long and thin elements of magnetic material. Or by using a magnetic material having a lower aspect ratio. Proper processing of the area, for example, a generally rectangular patch of spin-fused magnetic material It can be obtained by annealing in the longitudinal direction. Single axis considered In the case of the position sensor, there are five degrees of freedom (x, y, z and two angles (centered on the axis). The rotation of the marker does not have any effect)). Three orthogonal complete sets of coils By performing three scans of a uniform DC magnetic field on each of the sets of You can get enough information. The first scan is without the magnetic field from the other set, The second scan is with a uniform DC magnetic field from one of the other sets and the third is These DC magnetic fields are used. This gives a total of 9 scans, which are Can be represented as in the table, where the magnetic field sources are identified as a, b and c Scans are numbered 1-9 (scan order is not important). The only information needed from each scan is the harmonic output from the marker in that scan It is the center position. Next, these nine DC magnetic field values are the xyz-theta -Can be converted to Phi coordinates. First, before the head is put into the coil, the system Can be used simply by holding the marker at the desired position, then When the head is placed on the coil, the marker can be moved until the same signal is obtained .   An order that has the advantage of requiring less time to scan the area of interest An alternative to the following query is to continue the magnetic field gradient to scan in all directions of interest. It is to rotate. This drives three sets of coils with an appropriate continuous waveform Can be achieved by For example, the coils in the x, y and z planes are: Current I given by_x, I_yAnd I_zIf driven by Occurs.   I_x= Cosω_at (Acosω_bt-sin ω_bt. sinω_ct)                                         −sin ω_at. cosω_ct   I_y= Sin ω_at (Acosω_bt-sin ω_bt. sinω_ct)                                         + Cosω_at. cosω_ct   I_z= Asin ω_bt + cosω_bt. sinω_ct Where ω_a= The total frequency of rotation of the applied magnetic field         ω_b= Null scanning frequency         ω_c= Inquiry frequency         A = amplitude ratio ω_b: Ω_c Typical (but not limiting) values of these parameters are as follows:         A = 10;         Frequency ratio ω_a: Ω_b= 1: 10; and         Frequency ratio ω_b: Ω_c= 1: 400Description of the drawings   The present invention will now be described with reference to the accompanying drawings.   FIG. 1 shows the basic elements of the tag reading system of the present invention.   FIG. 2 is a circuit diagram showing one mode for generating a desired magnetic field pattern in the arrangement of FIG. It is a road map.   FIG. 3 relates the magnetic response of the tag to its location in the reading system of FIG.   FIG. 4 shows where magnetic nulls occur in permanent magnets.   FIG. 5 utilizes coils and permanent magnets to generate a desired magnetic field pattern. 1 shows an embodiment of the present invention.   FIG. 6 utilizes a pair of permanent magnets to generate a desired magnetic field pattern. 1 shows an embodiment of the present invention.   FIG. 7 shows an annular array with coils to generate the desired magnetic field pattern. 1 shows an embodiment of the present invention utilizing a plurality of arranged permanent magnets.   FIG. 8 is a schematic circuit diagram of one embodiment of a tag introgator according to the present invention. is there.   FIG. 9 shows the selection of a tag according to the invention.   FIG. 10 illustrates an embodiment of the present invention as applied to a surgical procedure.   Referring to FIG. 1, a schematic arrangement is shown, where tag 1 has two coils Tx 1 and Tx2. The tags are of the type shown in FIG. That is, each magnetic alloy material having high magnetic permeability, for example, about 10^FiveIntrinsic permeability of Magnetic, which is a vacuum schmerze 6025 spinning fusion ribbon with high modulus It is a simple linear tag with elements. In connection with the elements shown in FIG. The values given in this description for various parameters are given only for the sake of example. It has been obtained by the reader and represents one useful example. Be recognized. The units for these parameters are the overall size of the system and its intent. Inevitably changes according to the function being performed. Construct a separate magnetically active region of the tag The magnetic element has dimensions of 10 mm x 1 mm x 25 microns and the adjacent elements The spacing between the elements is 1 mm. The two coils are separated by about 20 cm , Each typically 0.56 mm wound into a 45 cm × 45 cm square shape 450 rotations of the copper wire. Each coil has a 6 ohm resistance and a 100 mH And a conductance. Each of the coils Tx1 and Tx2 is DCICarry Smaller exchange aboveiAre typically stackedIIs a 3A order , Stacked exchangesiIs on the order of 50 mA. Alternating currentiIs a relatively high frequency, The frequency is about 2 kHz.   In a system as described above, the alternating and direct currents in the two coils are magnetic fields Generate a pattern, where there is a point in the plane between them, parallel to the two coils ArrowxMagnetic null exists in the direction of. In FIG. 1, the x-coordinate and y-coordinate of this intermediate plane are shown. The markers are represented by lines 2 and 3, respectively.   The magnetic tag of the present inventionxGenerally defined between the center points of the two coils Is moved along the longitudinal axis to be passed through the two coils shown in FIG. If so, this is the field polarity reversal at the intermediate plane defined by coordinates 2 and 3. To experience. The change in polarity of the magnetic field is indicated by the bold arrows in FIG. As such, a DC current flows in one direction in the first coil and the opposite in the other coil. This is because it flows in the direction. In the intermediate plane, the direct current flowing through the first coil The generated magnetic field component is the magnetic field component generated by the direct current flowing through the other coil. Just offset.   As the tag moves through the center of the first coil, it becomes magnetically active. Experience a high magnetic field that is sufficient to saturate the When moving down, the magnetic material is shown by its hysteresis curve Affected by the decreasing magnetic field. In the vicinity of the magnetic null, the magnetic element of the tag The magnetization direction of the element is reversed.   The relatively high frequency AC i shown in FIG. 1 is applied to each of the coils Tx1 and Tx2. Are the same.   The alternating current can have a wide range of frequencies as described above, and in the arrangement of FIG. Is about 2 kHz. The effect of this relatively low amplitude AC is The intermediate plane defined by the markers 2, 3 is the length defined between the center points of the two coils This is to oscillate about a geometric center point along the hand axis. In other words The plane containing the magnetic null oscillates back and forth in a small spatial region at the alternating frequency. Wobble.   FIG. 2 shows a simple circuit for providing an opposite DC magnetic field combined with an AC magnetic field. You. Capacitor C1 is an inductor of coils Tx1 and Tx2 at AC drive frequency The coils are selected to resonate, each of these coils having a 6 ohm resistance and 1 It has an inductance of 00 millihenry. Typical values for C1 are 0. 1 μF. C2 is selected to act as a valid short circuit at the AC drive frequency. A typical value for this component is 22 μF. You. DC power supplies typically provide 30 volts at 3 amps, AC sources typically supply 2 volts.   AC is applied at a frequency of 2 kHz at rms.   FIG. 3 shows that the magnetization of a single magnetic element is between the coils Tx1 and Tx2 of FIG. How it changes with time at different locations within the magnetic field pattern specified in Show. For easy illustration, the oscillation of the surface containing the magnetic null is a thick double head And the center point between the limit surfaces 5 and 6 is represented by the dashed line 7 . At the right position in FIG. 3, the applied AC magnetic field is positive (H₊) And negative (H_-) And changes with time between the values shown in FIG. Graph of the applied AC magnetic field Below, the net magnetization of the magnetic element is shown on the left as position 1, position 2, etc. 5 showing how it changes over time at each of the five geometric locations There are two graphs. Surfaces 5 and 6 define the limits of the area where the reversal of the magnetic field polarity occurs I do. As a practical matter, the spacing between surfaces 5 and 6 is typically on the order of 1 mm. Yes, for a given magnetic material, this distance is dependent on the AC current in the coil and / or Can be optionally reduced or increased within a certain range by changing the amplitude of the DC current You.   The magnetic element always has a linear magnetic axis perpendicular to the planes 5, 6 and 7.   In position 1, the end of the magnetic element is adjacent to the surface 6, in this state Magnetic elements always experience a positive magnetic field and their net magnetization changes with time do not do. At position 2 the tip of the element reaches the intermediate plane 7. But magnetic Most of the gaseous material is still outside the critical plane 6. Therefore, the null surface is magnetic Can interact with only a portion of the gaseous material and, as a result, The net magnetization has a repeating pattern as shown, i.e., the portion of the straight positive value , After which it falls to zero and then rises to its original positive value, generally Has a sinusoidal arc.   At position 3, the magnetic material is positioned symmetrically with respect to the intermediate plane 7. here , The plot of net magnetization versus time has a frequency corresponding to the frequency of the applied AC magnetic field Including sine waves. At position 4, most of the magnetic elements always experience a negative magnetic field However, a small part of the element experiences polarity reversal, which A plot of such net magnetization versus time is obtained. Position 4 is actually the inverse of position 2 What is reflected in the relationship between the magnetization plots of these two locations is that The plot for 4 is actually a mirror image of the plot for position 2, but the curve You will see that the minutes have shifted in time.   Finally, at position 5, all tags experience a negative magnetic field, and No part experiences a reversal of field polarity. Therefore, the net magnetization changes with time Rather, it is a constant negative value as shown.   A tag containing such a magnetic element passes through the zero field region along the axis of the coil When it does, it will initially be completely saturated by the DC magnetic field. Next, the tag Are driven on the BH loop when passing through the zero magnetic field region. Finally it Will saturate again. The part over which the magnetic material moves is "active" That is, this part experiences a magnetic change, is physically small, and has a DC magnetic field amplitude. It is determined by the width, the amplitude of the AC magnetic field and the properties of the magnetic material. The size of this area Can easily be made smaller than 1 mm. The level of the alternating magnetic field is If the tag is well below the level required to saturate the material, the tag will 1) and 2), responding to the changing magnetic field, the tag causes the harmonics of the AC signal to change. Wave Will occur. When the tag straddles the narrow zero magnetic field area (position 3), the tag Driven on the linear part of the BH loop and diverging only the fundamental reference frequency And interact with. Next, when the tag exits the zero field region (from position 4 to 5), It will again generate harmonics of the interrogation field frequency.   A receiver (Rx) coil having sensitivity to a magnetic field generated in a zero magnetic field region. Tall, but not directly coupled to introgator (Tx) coil One will only receive these signals. Such a configuration has low mutual coupling Using separate Tx and Rx coils physically located to have Combines a single coil (having both Tx and Rx functions) with Tx and Rx Can be achieved by using it with appropriate filtering in the road. Can be. Changes in this signal due to the time the tag passes along the axis of the coil , 0 through the magnetic field region are clearly shown.   The result of such an interaction between the tag and the magnetic field it experiences is shown in FIG. Is done. Here, the region 4 where the magnetic null oscillates is shown in a reduced size. Represents the middle location of the tag at each of positions 1-5. (Second high of applied frequency The generation of harmonic signals by the tag (indicated by the harmonics) indicates that the tag In the zone defined by steps 6 and 7, ie the zone where the field reversal occurs. It is clear in. Due to the symmetry of the system, a single magnetic element Two peaks 8a and 8b will occur. This is because positions 2 and 4 Due to redundancy.   Referring now to FIG. 4, the line of force (ie, magnetic Is shown). The plane XY, which intersects the vertical axis of the bar-shaped magnet and is perpendicular to the paper surface, As a result, a magnetic null surface is formed. Therefore, they are arranged orthogonal to the null plane. The magnetic element having the sensitive magnetic axis can be in the path AB or the path CD. You will experience magnetic nulls as you cross over. Because of this, such magnetic Detect the presence of a tag or read information conveyed by such a tag To this end, a simple bar magnet can be used as part of the inquiry system.   Underlying the tag detection system by generating a second harmonic signal Can be. The tag is not just a single magnetic element, If a linear array is included, the second harmonic output from the tag will be twonPeak And each type is shown in FIG. 3b. Size of magnetic element If the magnetic properties are exactly the same, the peaks should have the same profile. And each peak defines the envelope of a certain area . Due to the space between the individual magnetic elements, two Will be affected. Just like this just mentioned It will be appreciated that the invention is not limited to the use of simple tags. Different Size and magnetic properties, and uneven space along the length of the magnetic tag Use of magnetic elements with Again, these patterns are characteristics of a given tag construction. Number, magnetic characteristics By changing the nature and position of a series of magnetic elements, And each of them has its own unique properties, and therefore FIGS. 1 to 3 That can produce unique signals when used in connection with other systems. It is possible to   Further, the invention is limited to observing the second harmonic of a given alternating frequency. It will be appreciated that this is not possible. This particular harmonic was selected for illustrative purposes. Have been. Because it has no (or very little) second harmonic content Since the generation of the transmission signal (Tx output) is relatively easy, the Tx signal and the tag response Can be distinguished sufficiently, and furthermore, this frequency is output from the tag. This is because it accounts for a relatively large proportion of the total of the obtained harmonic energies.   Referring next to FIG. 5, there is shown a schematic configuration of a simple tag reader according to the present invention. The reader comprises a permanent magnet 10 and a coil placed adjacent one face of the magnet. 11 is used. In this embodiment, the tag to be read is It may pass along path CD or path AB on the coil. Tags are those magnetic The axis must be oriented to align with the direction of tag movement. In FIG. As shown, the magnetic null plane is located at 12.   Referring now to FIG. 6, two permanent magnets whose magnetic axes are aligned and Is shown for use with a similar pole opposite to. With such a configuration, the null surface 13 And the required direction of tag movement is indicated by arrow 14. Again, the tag The magnetic axis must be aligned with the direction of movement. FIG. 7 shows that a magnetic null surface is generated. 1 shows a simple embodiment of a tag reader head using a plurality of permanent magnets. As shown Next, ten polymer-bonded ferrite magnets face inward facing similar And arranged in an annular array. As shown, a common transmit / receive coil L1 is placed in the ring of the magnet. The tag is located at the center of the magnet loop. Is read when passing through the surface.   Referring now to FIG. 8, there is shown one embodiment of a query system according to the present invention. You. This means that the single coil L1 can be connected to a transmitter ( Use to act as both a Tx) coil and a receiver (Rx) coil based on. The system uses the tag's secondary as a criterion for tag detection / identification. Use the harmonic output of Circuit components C1 and L2 are at frequency 2f To form a resonant trap to reduce this frequency signal at the Tx output to a very low level. C2 resonates with L1 at the frequency f, and the component C3 , C4, L1 and L3 form a filter for transmitting the signal at the transmitted frequency f. At frequency 2f, the required signal is passed from the tag while rejecting the signal.   The output from this circuit passes through a low-pass filter and is converted to analog-to-digital. To a digital signal processor (ADC). These components Components and especially the signal processor should be compatible with the intended use of the interrogation device. Will be composed. The nature of signal processing and the means by which it is achieved are all conventional Since this is the technique described above, it will not be further described here.   FIG. 9 shows a basic structure of a magnetic tape according to the present invention. FIG. 9a shows tag 1 00 and the tag 100 is a carrier medium (eg, of paper or plastic material). Linearity of body 101 and magnetically active regions 102, 103, 104, 105 and 106 And an array. Each magnetically active region (eg, vacuum schmerze 602) 5) is formed from a patch of highly permeable magnetic material, the magnetic axis of which is along the length of the tag. Align. The area of each patch is about 10mm^TwoAnd adhered to the substrate 101 to be fixed. Is determined.   The size and magnetic properties of the patches 101 to 105 are the same and uniformly The paced gaps 110, 111 and 112 are all the same. However, one patch is missing at the position indicated by the dotted line at 113. The gap between patches 105 and 106 is large.   Tag 100 acts as a 6-bit tag coded as 111101 ( 0 is the area 113).   A functionally equivalent tag 120 is formed from a substrate 121, which is a magnetic element. 122 through 126 and has a “gap” 127. In this example And the magnetic element is high (eg, Vacuum Schmelze 6025). In the form of strips or wires of permeable magnetic material, typically about 5 m in length m, a width of 1 mm, and a thickness of about 15 microns.   FIG. 9 b shows an alternative configuration of the 6-bit laminate tag 130. This tag It is coded into 111101 as in FIG. 9a. Where the continuous layer Or highly permeable magnetic material (in the form of wire, strip, thin film or foil) The length of the material 131 and the substrate 133 sandwich the magnetic bias layer 132 between them. I do. The bias layer is magnetized in a predetermined area, which is 134, To generate magnetically active regions indicated by 135, 136, 137 and 138, Affects the overlying high permeability material. Region 139 is not active and therefore has a zero magnetic field. Make the world. When read by the inquiry system as shown in FIG. The outputs generated by 0 and 130 are shown in FIG. 9d.   A more complex tag is shown in FIG. 9c. Here, a series of parallel Linear arrays exist, which generate a 4 × 4 array, where the magnetically active Area is present (coded as "1") or not ("0 ").   FIG. 10 illustrates three sets of coils used in accordance with the present invention for a surgical application. Shows a general configuration. All three coils are arranged orthogonally to each other, A cavity is defined in which the patient's head 200 is located. obtain. The first set includes coils 201a and 201b, and the second set includes coils. The third set includes coils 203a and 203b. Including. In the figures, two surgical probes 204 and 205 are connected to the patient's skull. And is schematically illustrated. Each of the probes has at its end, for example It has magnetic tags 206 and 207 as described with reference to FIG. 9 above. The magnetic element of the tag contains information about its presence (rather than holding extended data). Relatively simple tags are preferred because they are only needed to provide information. High permeability It is sufficient for a single magnetic element of magnetic material to be placed at the tip of the probe. You. The coil operates in the manner described in detail above. According to the present invention, the probe Determine the positions of both ends with high precision, and perform various complicated procedures accurately and correctly. It can be implemented to minimize damage to the device.

[Procedure amendment] [Submission date] December 2, 1997 [Content of amendment] Claims 1. A method for querying a magnetic element having non-linear magnetic properties, comprising: (1) applying a magnetic field to a region where the magnetic element is located or expected to be located, resulting in a magnetic null defined in said region. (2) causing relative motion between the magnetic field and the magnetic element such that the magnetic element crosses a magnetic null or vice versa; and (3) the magnetic element during the relative motion. Detecting the magnetic response of the magnetic element. 2. The method of claim 1, wherein the magnetic null is near an area where there is sufficient magnetic field to saturate a magnetic element or a portion thereof. 3. 3. The method of claim 2, wherein (a) the magnetic null is in a plane, and (b) the saturation field is generated proximate to the plane. 4. The method according to claim 1, wherein the magnetic null is caused to sweep back and forth in a part of the area. 5. Method according to claim 1, 2, 3 or 4, characterized in that the relative movement is caused by causing the magnetic element to cross an interrogation zone where the required magnetic conditions are generated. 6. Method according to claim 1, 2, 3 or 4, characterized in that the relative movement is generated by sweeping an applied magnetic field over a magnetic element. 7. A method according to any of the preceding claims, wherein the magnetic element is generally elongated and the zero field direction of the magnetic field extends along the main axis of the magnetic element during the relative movement. 8. A method according to any of the preceding claims, characterized in that the magnetic element is in the form of a thin film or foil, and the zero field direction of the magnetic field is aligned with the axis of magnetic sensitivity of the relative motion media. 9. Method according to any of the preceding claims, characterized in that the magnetic field is established by applying two magnetic fields of opposite polarity to the area. 10. 10. The method of claim 9, wherein the application of the two magnetic fields is performed by using one or more coils that carry a direct current. 11. Method according to any of the preceding claims, wherein the magnetic field is established by using one or more permanent magnets. 12. The method of claim 10, wherein the one or more coils carry a substantially constant current. 13. 11. The method of claim 10, wherein the one or more coils carry a current that varies in magnitude in a predetermined cycle, so that the position of the magnetic null oscillates in a predetermined manner. the method of. 14． Since the one or more permanent magnets involve one or more coils that carry a current that varies in magnitude according to a predetermined cycle, the position of the magnetic null may oscillate in a predetermined manner. The method of claim 11, wherein the method is characterized by: 15. A method according to any of the preceding claims, wherein the relative movement is caused by applying an alternating magnetic field to the magnetic field. 16. 16. The method of claim 15, wherein the relative motion between the magnetic field and the magnetic element is caused by applying a relatively low amplitude alternating magnetic field superimposed on a DC magnetic field. 17． 17. The method of claim 16, wherein the relatively low amplitude alternating magnetic field has a frequency in a range from 10 Hz to 100 kHz. 18. Detecting a magnetic response of the magnetic element includes observing a harmonic generated when the magnetization state of the magnetic element changes by passing through a magnetic null from the applied AC magnetic field. A method according to any of the claims. 19. A method for determining the position of an object, comprising: (a) fixing a small piece of magnetic material to the object; and (b) applying a magnetic field to an area where the object is located, resulting in a magnetic null defined herein. (C) causing a relative movement between the magnetic field and the magnetic material such that the magnetic material crosses a magnetic null or vice versa; and (d) the applied magnetic field and the magnetic material Observing the magnetic interaction with the magnetic material; and (f) calculating the position of the object from the consideration of the magnetic interaction and from the applied magnetic field and known magnetic parameters for the small pieces of the magnetic material. Determining the position of the object. 20. 20. The method of claim 19, wherein the magnetic field is caused to repeatedly traverse a magnetic material as a result of applying a low amplitude, high frequency interrogating magnetic field to the region. 21. 21. A method as claimed in claim 19 or claim 20, wherein the magnetic field is generated by three sets of mutually orthogonal magnetic field sources, and then calculating the location of the center of the harmonic output from the magnetic material for each scan. 22.3 continuously exciting three sets of orthogonal coils to produce a continuously rotating magnetic field direction covering a volume of interest in a controlled sweep of a predetermined width; A method according to claim 21. 23. A method of coding and / or labeling individual articles in a predetermined set of articles according to data indicating the characteristics of the articles, for example, the price of the articles and / or the nature of the commodities making up the articles, wherein A magnetic tag or marker having a predetermined arrangement of magnetic zones specific to articles and others that share characteristics such as, for example, the price of the articles and / or the nature of the goods that make up the articles. Wherein the magnetic tag or marker is susceptible to an inquiry according to the method of claim 1 and generates a response indicative of the magnetic properties of the tag or marker, and thus indicative of the nature of the article having the magnetic tag or marker. A method of coding and / or labeling an article of matter. 24. 2. A method for summing data (e.g., price) from a collection of individual articles each having a magnetic tag susceptible to inquiries according to the method of claim 1, wherein the tags are specific features of the article to which the tag is attached (e.g., price) ), The collection of articles being adapted to travel through an inquiry zone to which the collection applies the method claimed in claim 21 or 22 , and to process signals received during said method. Summing the individual data values to produce the required sum. 25. An apparatus for reading a magnetic tag, the apparatus comprising a plurality of permanent magnets arranged in a circular array around a gap, wherein the tag to be read is able to pass through the gap, wherein the poles of the permanent magnet are: The magnet is arranged such that one polarity (eg, north) pole of each magnet is positioned inside the circular array and the opposite polarity (eg, south) pole is positioned outside the circular array, and the coil is An apparatus for reading a magnetic tag, arranged coaxially with said circular array in proximity to a magnet. 26. 26. The device of claim 25, wherein said permanent magnet is a polymer bonded ferrite magnet. 27. Apparatus for interrogating magnetically coded tags, characterized in that the apparatus is characterized by an electric circuit comprising a signal source of frequency 2f and output means for providing an electric output, said source being connected to said output means. (I) means for halving the frequency of the source signal, (ii) first filter means substantially arranged to reject signals of frequency 2f, and (iii) frequency a transmitter coil tuned to the energy of f and radiating energy toward the magnetically coded tag, and a receiver coil for receiving energy radiated by the tag in response to the received energy (see above). The same coil as the transmitter coil), and the magnetically coded tag is radiated by the transmitter coil. Coupled by tuning circuit means arranged to be affected by the lugi and (iv) second filter means arranged substantially to reject energy at frequency f and pass energy at frequency 2f; The output means is magnetically coded, arranged to provide an output that is a function of the amplitude of the output of the second filter means and the phase difference between the source and the output of the second filter means. A device for querying tags. 28. A magnetic marker or tag characterized by a substrate having a plurality of discrete magnetically active regions arranged in one or more linear arrays, the magnetically active regions being the (or individual) magnetically active regions. A magnetic marker or tag consisting of a thin film or spin-melted material with a preferred axis of magnetization aligned in a linear array. 29. 29. The tag of claim 28, wherein the magnetically active areas and / or spaces between the magnetically active areas are non-uniform. 30. The discrete magnetically active region is formed from a continuous region of discrete regions of magnetizable material that is magnetized to create a space between the magnetically active regions. The tag according to 28 or 29.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G06K 19/06 G06K 19/00 E (81) Designated country EP (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG) , AP (KE, LS, MW, SD, SZ, UG), AM, AT, AU, BB, BG, BR, BY, CA, CH, CN, CZ, DE, DK, EE, ES, FI, GB, GE, HU, JP, KE, KG, KP, KR, KZ, LK, LR, LT, LU, LV, MD, MG, MN, MW, MX, NO, NZ, PL, PT, R O, RU, SD, SE, SI, SK, TJ, TT, UA, US, UZ, VN

Claims (1)

[Claims] 1. Magnetic, characterized in that it holds a plurality of separate magnetically active regions in a linear array Marker or tag.